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@node Signal Processing
@chapter Signal Processing

This chapter describes the signal processing and fast Fourier
transform functions available in Octave.  Fast Fourier transforms are
computed with the @sc{fftw} or @sc{fftpack} libraries depending on how
Octave is built.

@DOCSTRING(fft)

@DOCSTRING(ifft)

@DOCSTRING(fft2)

@DOCSTRING(ifft2)

@DOCSTRING(fftn)

@DOCSTRING(ifftn)

Octave uses the @sc{fftw} libraries to perform FFT computations.  When Octave
starts up and initializes the @sc{fftw} libraries, they read a system wide
file (on a Unix system, it is typically @file{/etc/fftw/wisdom}) that
contains information useful to speed up FFT computations.  This
information is called the @emph{wisdom}.  The system-wide file allows
wisdom to be shared between all applications using the @sc{fftw} libraries.

Use the @code{fftw} function to generate and save wisdom.  Using the
utilities provided together with the @sc{fftw} libraries
(@command{fftw-wisdom} on Unix systems), you can even add wisdom
generated by Octave to the system-wide wisdom file.

@DOCSTRING(fftw)

@DOCSTRING(fftconv)

@DOCSTRING(fftfilt)

@DOCSTRING(filter)

@DOCSTRING(filter2)

@DOCSTRING(freqz)

@DOCSTRING(freqz_plot)

@DOCSTRING(sinc)

@DOCSTRING(unwrap)

@c FIXME: someone needs to organize these ...

@DOCSTRING(arch_fit)

@DOCSTRING(arch_rnd)

@DOCSTRING(arch_test)

@DOCSTRING(arma_rnd)

@DOCSTRING(autoreg_matrix)

@DOCSTRING(bartlett)

@DOCSTRING(blackman)

@DOCSTRING(detrend)

@DOCSTRING(diffpara)

@DOCSTRING(durbinlevinson)

@DOCSTRING(fftshift)

@DOCSTRING(ifftshift)

@DOCSTRING(fractdiff)

@DOCSTRING(hamming)

@DOCSTRING(hanning)

@DOCSTRING(hurst)

@DOCSTRING(pchip)

@DOCSTRING(periodogram)

@DOCSTRING(sinetone)

@DOCSTRING(sinewave)

@DOCSTRING(spectral_adf)

@DOCSTRING(spectral_xdf)

@DOCSTRING(spencer)

@DOCSTRING(stft)

@DOCSTRING(synthesis)

@DOCSTRING(yulewalker)
